The goal of this project is to characterize mechanisms of immunregulation of antibody synthesis and secretion, particularly Ir genes and idiotype networks. Recently, a system has been developed in which, for the first time, soluble antibody responses to the synthetic polypeptide (T,G)-A--L can be generated and detected in vitro using antigen-primed lymph node cells. Responses are antigen dependent and specific, and H-2 linked Ir gene regulated. Antibodies specific for the idiotypes of anti-(T,G)-A--L antibodies induce antigen-independant anti-T,G)-A--L antibody responses. These responses are specific at the levels of the anti-idiotype reagent, the antigen-priming, and the antibody produced. The anti-idiotype reagent stimulates function of both primed T helper lymphocytes (help) and of primed B lymphocytes (antibody secretion). The latter occurs in the absence of T lymphocytes.